* Exports down 4.2 pct
* EU is biggest trading partner, trade with EU falls
ZURICH Feb 5 Swiss exports fell in December, data showed on Tuesday, dragged down by weak demand from the country's top trading partner Europe.
Exports adjusted for the number of working days fell by 4.2 percent to 14.049 billion Swiss francs ($15.46 billion), the Federal Customs Office said on Tuesday.
Unadjusted sales of goods to Europe - Switzerland's biggest trading partner - dropped 10.2 percent, while sales to Asia fell 8.6 percent.
Exporters have benefited from the Swiss National Bank's cap of 1.20 francs per euro in place since September 2011, but they have also faced headwinds from weak demand in the neighbouring euro zone as the region's debt crisis hit confidence and output.
Despite the drop in exports in December, a raft of other data has suggested the Swiss economy may have emerged from a trough since the start of the year.
Swiss manufacturing activity expanded for the first time in 17 months in January, while investor sentiment showed a further improvement last month.
Rising confidence that the euro zone will shake off its sovereign debt crisis also saw the franc weaken in January, providing some cheer for exporters who have long complained the cap was set too high, eroding their margins.
The franc is some 30 percent stronger than it was before the financial crisis erupted in 2008 and Switzerland's finance minister has said it remains overvalued.
Overall, Switzerland ran a merchandise trade surplus of 1 billion Swiss francs in December.
($1 = 0.9086 Swiss francs) (Reporting by Caroline Copley: Editing by John Stonestreet)